US1994983A - Apparatus for indicating and/or controlling physical changes - Google Patents

Description

March 19, 1935.

y L. DE FLOREZ ET AL 1,994,983 APPARATUS FOR INDICATING AND/OR CONTROLLING PHYSICAL CHANGES Filed Jan. 27, 1931 2 Sheets-Sheet 1 INVENTORS 10/: de flare: 4 imman Fae/7.

BY w t F/ca.

#M/ ATTORNEYS March 19, 935- v DE FLOREZ ET AL 1,994,933 APPARATUS FOR INDIbATING AND/OR CONTROLLING. PHYSICAL CHANGES Filed Jan. 27, 1931 2 Shets-Sheetfi m ATTORNEYS Patented Mar -19,1935; I t Y UNITED STATES PATENT OFFICE M 1,994,983 7 I I r Armnsrus ron INDICATING AND/OB con- 7 'raommo PHYSICAL cannons Luis de Flores, Pomfl'et, com, and Emmon Bach, New York, N; Y., said Bach ass'ignor to said -de Florez Application has 27, 1931,. Serial No. 511,552 10 Claims. (01.236-99) This invention relates todevices for indicating, Figure I shows' a form of the invention in recording and controlling physical changes with which the apparatus is responsive to temperarespect to the rate as well as the degree of such ture and temperaturechanges, together with an change. In its broader and more general asillustrative adaptation .thereof to temperature pects the invention is concerned with an apcontrol;

paratus which will respond to changes in the Figure II is a graphical representation of-the physical condition of acontrolled system comoperating characteristics of the invention inconmunicating therewith, in accordance with the nection with the indication and/or control of characteristic timerelationships, within said physical changes;

system, between operating factors and the ef- I Figure III shows a modification wherein the 10 feet thereof. More particularly the invention apparatus is responsive to pressure temperaprovides a novel combination of mechanical deture or temperature changes;

vices, the movement or which, at a time of pres- Figure IV shows a further modification of the sure or temperature change, will initiate and invention (8 80118 0 t e form Shown in maintain a pressure or temperature regulating Figure I) responsive to temperature and temoperation based upon the rate of such change and Den r ch n an anticipating the full extent thereof. Figure V w a broken det l of a odifica- The present invention, while of general aptic 0 the control apparatus shown in plication in the field of pressure or temperature ure III.

measurement, has particular industrial utility in Referring now to Fig I h apparatus 20 connection with pressure or temperature conp i tWO mechanical devices 10 and 11, mOVetrol. The successful operation of many indust n which is'occasioned y ha s in pr trial processes is conditioned upon maintaining mp a p rating a re ulat ry m h a substantially constant pressure or temperanism 12 through the medium of the lever 13.

ture, and it is therefore desirable to utilize a. con- In the Particular modification Sh the 25 trol system which will operate to prevent physichanical devices 10 and 11 comprise the collapscal changes or undue magnitude and duration ible bellows 14 and transmitting pressure as well as occasioning a return to no l after through the rods 16 and 17 to the lever 13 at a change has occurred. Such processes furthe contact points 18 and 19. Two vessels, 20

ther are usually characterizedby an interval and 21 (which may conveniently be in the form 30 between the time of occasioning a regulatin of elongated cylindrical tubes), containing heat change in operation and the time when the full Sensitive fluid, are located in the desired process eirect thereof is felt atthe point of pressure t atu e zone, and communicate with the or temperature control. This time interval is bellows 14 end 15 through the P p s 22 d 23 appreciableand induces the familiar phenome- ,respectively- The Vessels a e u j d o the 35 non of hunting in a control system which is Same process mp t h l r p n based solely upon the instantaneous values of of the vessel 21 thereto is delayed by surroundprocess pressure or temperature without regard ihg it With thermel insulation 24 to a d the to the rate of change therein and which makes flow of heat to and from this vessel.

no r vision for compensating, to any extent, The bellows 14 and 15 are mounted on the 4 the characteristic lag or the process, Thi i fixed support 25 andconnect with the lever 13 vention contributes materially to the improvethrough the reds mend p y' tt d me t of pressure or temperature control ysto said lever at the points 18 and 19 respectively. terns by providing a means of initiating regu1a,- The fixed support 26 carries the sleeves 2'7 and tory steps, at a time of physical change, which 38 acting as u des for the rods 16 a d 7- A are more than is proportionately necessary to lusting nuts 29 and threaded 0n the Sleeves counteract the initial extent of such change and 7 n provide means for e u at the then proportioning the compensation of the initension in the springs 31 and 32 mounted theretial over-correction to the rate of the return to e Said p s respectively determine h 59 normal in the physical condition of the process p i i c the Points 13 and 19 0f the level '50 under contr with respect to the pressure within the bellows In the accompanying drawings, which pre- 14 and sent several applications of the principles un- In the depicted mode of adapting this form of derlying the invention (like reference characthe invention to temperature control, the free ters denoting like parts), end 0! the-lever 13 operates a regulatory mechgree of valve opening which will occasion a fuel supply necessary to establish and maintain such temperature values under static process conditions. Thus the desired process temperature datum level may be easily and simply regulated to accord with occasional or periodical changes in the operating characteristics of the process.

When the form of the invention shown in Figure '1 is adapted to its intended use, the tubes 20 and 21 are placed in an industrial vessel or conduit in such a manner as to locate both of said tubes in the same process temperature zone; The fluid spaces of the said tubes are of the same dimensions and the heat" sensitive fluid contained therein is of the same amount and composition. The said fluid is of such a character that its vapor pressure is substantially proportional to the temperature to which it is subject-, ed, and thus the resulting pressures in the tubes 20 and 21, respectively, will be identical whenever the fluid in the tube 20 is at the same temperature as the fluid in the tube 21. tion of pressure equilibrium withinthe apparatus corresponds to a constant-process temperature period, and during such a period the lever 13 lies in .a horizontal plane at a level dependent upon and indicative of the magnitude of the constant process temperature, provided that the springs 31 and 32 have been adjusted to the same tension.-

If an increase in process temperature occurs,

the full response of the fluid in the tube 20 will be substantially instantaneous while the full response of the fluid in the tube 21 will be delayed. Consequently a temporary pressure differential is set up between the device 10 and the device 11 which causes a'movement differential between the points 18 and 19 respectively, and hence the lever 13 moves away from the horizontal. The appartus is so calibrated that the position of the point 18 continuously measures instantaneous values of the process temperature, and the movement of the lever 13 at said point is a measure of the actual change in process temperature The movement of the free end of the lever 13 will then represent a magnification of the process,

tion being a function'of the distance of said free end from the point-l8 (at. which point the magnification is zero). v The actual amount of such magnification, for any given point on the lever 13 to the right of the point 18, is a function of the angle said lever makes with the horizontal.

As long as the process temperature is changing either away from or back to its datum'level), the point 18 on the lever-l3 will lead the point 19, since process temperature values are reflected immediately at the point l8while the response of the point 19 to the same process temperature values is delayed for a time interval corresponding to the temperature response lag between the tubes 20 and'21. The tendency of movement at horizontal position at the-original level thereof.

lhus the angle of the lever 13 with the hori- Such a condizontal, during a period of process temperature change, will vary continuously during such period and at a rate proportional to-the temperature change rate. The amount by which the process temperature change is magnified in the movement of the lever 13 at its free end will therefore vary in accordance with the rate of such change.

Assuming that the regulatory mechanism controls fuel supply, the setting of the screw 33 relates normal fuel supply to normal process temperature and as long as the lever 13 is at the proper horizontal level the control valve 12 will maintain a fuel rate corresponding thereto. Movement of the free end of the lever 13 is transmitted directly to the mechanism 12 occasioning a movement of the valve stem 34. When the lever 13 is at an angle to the horizontal, the valve 12 will therefore pass an amount of fuel which is more than that proportionately necessary to maintain the actual instantaneous process temperature, when that temperature is decreasing, and which is less than the proportionate amount when the said temperature is increasing. Thus the device provides for the compensation of the characteristic process lag by magnifying the effect of .a temperature change in the response of the control mechanism, thereby initiating a return to normal process temperature at a rate which will inhibit any substantial further temperature change in the original direction. In other words, the change in fuel supply (or other regulatory operation) leads the process temperature change during the period of change by an amount proportional to the rate of such change.

The preceding discussion of the operation of the form of the invention shown in Figure I in connection with thecontrol of temperature is premised primarily upon-1a condition of positive initial temperature change. When the initial process temperature change is negative (that is to say a'decrease) the functional operation of the apparatus is the same as for an increase in temperature. The movement direction of the several units thereof will, however, be in the opposite direction at the various stages of the operation. I

I A graphical representation illustrating the movement reactions of the apparatus when adapted to its intended use is shown in Figure II. Time is plotted against movement magnitude and several conditions of varying process temperature are shown. In the figure the solid line represents the movement of the point 18 on the lever 13 corresponding to the actual process temperature, and the broken line represents the movement of the free end of the lever, 13 corresponding to a magnification of the, process temperature in accordance with the rate of change thereof. It will be noted that the broken .line merges with the solid line during periods of thermal equilibrium corresponding to a horizontal position of the lever 13.

When the apparatus is functioning merely as an indicating and/or recording device the sections of Figure II marked "a", b" and 0" respectively i1- lustrate its performance under various process temperature; conditions- At a an abrupt increase in process temperature to a new constant level is outlined by the movement of point-18 along the solid-line of the figure. Since the full movement response of the point 19 is delayed, the

movement of the free end of the lever indicates a magnification of this temperature change along in amount since the .change occurred abruptly. The movement of the point 19 gradually brings the lever 13 to a horizontal position corresponding to the new temperature level, thusreducing the movement differential in the apparatus to zero and effecting a merger of the solid and broken lines in Figure It. At b" the response of the apparatus to an abrupt process temperature such as fuel supply. In passing it may be noted that the ordinates of Figure II maybe considered as representing temperature values as well as movement magnitude of points on the lever 13 corresponding thereto. In the figure "250 indicates the predetermined process temperature datum level which is desired and which the control system has been set to maintain. As long as the temperature remains at this level the control system is static since vessels 20 and 21 are both responding fully to the same temperature. Assume now that the process temperature suddenly decreases toward the value t" a resulting movement differential between the device and the device 11 occasions a magnified response to.

this change in the regulating mechanism 12 by reason of the magnified movement of the free end of the lever 13; An increase in fuel supply to the unit, at a time and to a degree suficient to prevent the process temperature dropping substantially below the point "t, is ediately established. The time temperature relations of the process and process equipment, to which the movement characteristics of the control apparatus have been correlated, determine the amount by which the fuel supply is increased over that proportionately necessary to ofiset the actual temperature change, in order that the time interval, which must elapse before the efiect of in crease in fuel supply is felt at the point of temperature control, may be compensated. This overcorrection will vary in amount as the process temperature returns to normal in accordance with the rate at which such return progresses. Thus, as the processtemperature increases from the point 2" in its return to the datum level to, the increase in fuel supply will diminish and since the change in fuel supply leads the change in temperature, the fuel supply increase will pass,

through a zeropoint and become a temporary decrease, although the process temperature is still increasing. This will result in diiishing the rate of temperature return during the last stages thereof, occasioning in turn a second increase in fuel supply at a rate sumcient to bat ance this factor to the process temperature at the datum level. In the figure the broken line, which represents the movement of the free end of the leverlii, corresponds to the 1. e in fuel rate, the point :r:" corresponding to the mum increase in fuel; supply, the point p? corresponding to the maximum decrease in fuel supply and the-point p, representing a momentary horizontal positionof the lever 13 during the.

temperature regulating operation, corresponding to the point at which an actual decrease in fuel supply .is initiated, although the process itemperature is still increasing. It will-be noted that the regulatory operation of this'invention in controlling temperature is free from the familiarand undesirable phenomenon'of hunting common to many temperature control systems. A similar graphical analysis applies to the operation of the device when the initial process temperature change is an increase instead of a decrease, the

deviations-of the curves from the normal being opposite in direction in such a case.

In Figures III and-1V, two additional modifica tions of the invention are represented. In each case the effective functional operation is the same as that described in connection with the modi-' flcation shown in Figure I. The three depicted forms of the invention are also substantially alike with respect to details of structure, the

major diflerence between the three lying in the mode of ,oc'casioning the delayed response of one unit of the apparatus to the physical changes being indicated and/or controlled. In the form shown in Figure in the structural modification referred to makes the apparatus adaptable to indicating and/or recording either pressure or temperature changes whereas the forms'shown in Figures I and IV are adaptable only to temperature operation. In the three figures, like reference characters denote like parts.

Referring now to Figure III,- the, pipes'22 and 23 establish communication, between the apparatus and an external process pressure or temperature zone, through the t" 40 and the pipe 41. The pipe 42, which may be considered as an extension of the line 41 (or as a separate pipe connected therewith) is connected; in the depicted assembly, to tube 43 containing heat sensitive fluid of the character described; in connection with Figure I. The tube 43is placed in the desired process temperature zone and the fluidtherein responds fully and immediately to changes in process temperature since the said tube is not thermally insulated. In this form of the invention movement response delay in the device 11 is occasioned by providing the regulating valve to,

ced by the pipe 23, which creates a pressure differential between devices 10 and 11 at a time of process temperature change. The adaptation of form of the invention to process pressure changes simply involves connecting the pipe 41 by means of pipe at with fluid cc of an industrial vessel or conduit 4'? as shown in the broken detail Figural! instead of with the tube 43 as in the dras. apparatus will then be produced directly by the prams pressure instead of at a pressure translation of process temperature as in the first instance. In either instance the functioning oi. the several mmhanical units of the apparatus 1 is the r s as hcreinbefore described for Figure I.

The form of the invention shown in Fire IV The pressure in the controlis alsostructurally similar to the form shown in {'JIZ I and is with: adaptable only to tempera ure operation: The movement of the several parts oi the apparatus, in response to process temperature changes, is, however, actuated bythe pressure rwctions, to said changes, of heat sensitivefluid contained within the bellows 1e and 15. The t 20 and 21 of Figure I are thus dispensed with in the Figure IV m tion.

structural e in the apparatusnecessitates placing said apparatus directly in the pump esstemmrature zone, giving-this form of the invention special-applicability to the indication and/or control ofrelatively low .tem'ture processesv and (as, for example, controlling refrigerating operations, maintaining constant temperature conditions in dryers, and the like). A shield 45 completely surrounds the bellows 15 in Figure IV and retards the flow of heat to and from said bellows. The full response of the fluid contained therein is thus delayed and a movement differential is consequently established between the points 18 and 19 of the lever 13 at a time of process temperature change. In operation, the movement characteristics of this form of the invention corresponding to process temperature conditions are the same as those outlined under the discussion of'the form of the invention shown in Figure I. The graphical analysis of said operating conditions hereinbefore presented applies equally to any and all modifications of the invention.

It will be understood that the pressure and/or temperature changes which affect the apparatus of the invention may be the result of other physical changes within the system or process under regulation. In such instances the regulating apparatu s is responsive to and operates'through temperature and/or pressure as an intermediate agency for transmitting the effectof the process physical change to the control apparatus although such physical change may not be one of temperature or pressure.

We claim:

1. In an apparatus for controlling physical changes in a controlled system, two mechanical devices connected for movement in the-same sense and responsive to the same physical condition oi the controlled system, means for occasioning movement of one of said devices in full and immediate response toa change in said physical condition, means for delaying the full movement .response of the other of said devices to said physical change, the rate of movement of each of said mechanical devices being independent of the rate of movement of the other and occasioning a differential in rate oi! movement therebetween,

the-magnitude of said movement differential being a function of the rate of said physical change, and means for transmitting the eiTect of said movement differential to operation-control devices.

2. An apparatus for controlling physical changes in a controlled system, which comprises two mechanical devices connected for movement in the same sense and separately responsive to the same physical condition of the controlled system, means for occasioning movement of said devices, in response to a change in said physical condition, means for delaying the full extent of such movement response of one of said devices to occasion a diflerential in rate ofmovement therebetween, the magnitude of such diiIerential being a function of the rate of said physical change, and means for transmitting the eifect of said movement diflerential to operation-control devices.

3. An apparatus for controlling physical changes in a controlled system, which comprises two mechanical devices connected for movement in'the same sense and separately responsive to the same physical condition of the controlled system, self-contained means for occasioning movement of'said devices in response to a change in said physical condition, means for delaying the full extent of such movement response of one of said devices to occasion a differential in rate of movement therebetween, the magnitude of such difierential being a function of the rate of said physical change, and means for transmitting the effect of said movement difierential to operationcontrol devices.

4. An apparatus for controlling pressure changes in a controlled system, which comprises two mechanical devices connected for movement in the same sense and separately actuated by pressures responsive to the pressure of the controlled system, means for occasioning movement of said devices in response to a change in said pressure, means for delaying the full extent of such movement response of one of said devices to occasion a differential in rate 01' movement therebetween, the magnitude of such differential being a function of the rate of said pressure change, and means for transmitting the efiect of said movement difierential to operation-control devices.

5. An apparatus for controlling temperature changes in a controlled system, which comprises two mechanical devices connected for movement in the same sense and separately actuated by pressures responsive to the temperature of the controlled system, means for occasioning movement of said devices inresponse to a change in said temperature, means for delaying the full extent of such movement response of one of said devices to occasion a differential in rate of movement therebetween, the magnitude of such differential being a function of the rate of said temperature change, and means for transmitting the efiect of said movement difierential to operation-control devices.

6. An apparatus for controlling physical changes in a controlled system, which comprises two bellows devices connected for movement in the same sense and actuated by pressures responsive to the physical condition of the controlled system, means for occasioning movement of said devices in response to a change in said physical condition, means for delaying the full extent of such movement response of one of said devices to occasion a differential in rate of movement therebetween, themagnitude of such differential being a function of the rate of said physical change, and means for transmitting the effect of said movement differential to operation-control devices.

7. In an apparatus for controlling physical.

changes in a controlledlystem, two bellows devices connected for movement in the same sense and actuated by pressures responsive to the same physical condition of the controlled system, means for causing the pressure actuating one of said devices to vary in full and immediate response to a change in said physical condition,.

means for causing the pressure actuating the other of said devices to vary in delayed response to said physical change, the rate of movement of each of said bellows devices being independent of the rate of movement of the other and occasioning a differential in rate of movement therebetween, the magnitude of said movement diflerential being a function of the rate of said physical change, and means for transmitting the effect of said movement diflerential to operationcontrol devices.

8 In an apparatus for controlling physical changes in a controlled system; two devices connected for independent movement in the same sense in response to the same physical condition of the controlled system; a member movable in .the same sense by both of said members; means for occasioning movement of one of said devices full movement response of the other of said devices to said physical change, the rate of movement of each of said devices being independent of the rate of movement of the other and occasioning a differential in the rate of movement therebetween and the magnitude of said movement differential being a function of the rate of said physical change; operation-control means associated with said member and actuable thereby; means connecting said one device to said member for moving the latter to actuate said operation-control means in determined proportion to the extent or" change in said physical condition; and means connecting said other device to said member for simultaneously moving the latter to vary the actuation of said operation-control means thereby in accordance with the said differential between the rates of movement of said devices.

9. In an apparatus for controlling physical changes in a controlled system; two devices connected for movement in the same sense in response to the same' physical condition of the controlled system; a member movable in the same sense by both of said members; means for occasioning movement of one of said devices in full and immediate response to a change in said physical condition; means for delaying the movement-response of the other of said devices to said physical change, the rate of movement of each of said devices being independent of the rate of movement of the other and occasioning a differential in the rate of movement therebetween and the magnitude of said movement differential being a function of the rate of said physical change; operation-control means actuable by said-member; means connecting said one device to said member for moving the latter to actuate said opmeans thereby in accordance with the rate of change of said physical condition.

10.121 an apparatus for controlling physical changes in a controlled system; two devices connected for independent movement in the same sense in response to the same physical condition of the controlled system; a member movable in the same sense by both of said members; means for occasioning movement of one of said devices in full and immediate response to a change in said physical condition; means for delaying the full movement response of the other of said devices to said physical change, the movement of each of said devices being independent of the other and 'occasioning a difierential in the rate of movement therebetween and the magnitude of said movement differential being, a function of the rate of said physical change; operation-control means actuable by said member; and means connecting both of said devices to said member to form floating pivots for transmitting to said operation-control means the movement effected by the otherdevice for causing said member to actuate said operation-control means to an extent disproportionate to the extent of saidphysical change and proportionate to the rate of said physical change.

LUIS DE FLOREZ. EMMON BACH.

Images